Refractive keratoplasty is a surgical procedure to alter the cornea's curvature for the purpose of correcting the refractive error of the eye. The procedure can range from producing precise surgical incisions in the cornea to implantation of either a lathe cut alloplastic or human stroma lenticule. This application is directed toward an investigation in the use of alloplastic, specifically hydrogel, intracorneal lenses (ICLs) for refractive keratoplasty. Hydrogel materials are presently being used for extended wear contact lenses that are high (50-80%) in water content and are very permeable to solutes. Because of these characteristics, along with the ability to precisely lathe cut a given power and base curve, the non-reactive tissue response to hydrogels, stability and availability of material, it is an excellent choice as an ICL. Yet, it is a foreign substance to the body and will never be integrated into the tissue as human donor cornea may be. Human donor cornea is biologically the perfect choice as an implant material, but is more difficult to precisely lathe cut, offers a less reliable supply of material and possibly a less dimensionally stable lenticule. The efficacy of hydrogel ICLS will be evaluated by long term non-human primate clinical and morphological studies to define the predictibility and stability of the procedure. An optical analysis of the data will be performed to aid in predicting the surgical outcome. The effect of the ICL on corneal physiology such as scarring, swelling, pressure, stromal elasticity, oxygen consumption, etc., will be assessed. The physical characteristics of the hydrogel material, i.e., permeability, drug uptake and release, elastic properties, etc., will be defined. The work will establish the efficacy of hydrogel ICLs prior to human clinical trials.